Hi guys,
The car in question is an 84 300d that I am at my wit's end with. I've put so much work into it and it still has issues, so I'm thinking about just selling it for parts but here goes:

I have a leak at the dipstick where it goes into the pan. Seems simple enough, just pull it out, new o-ring, back in. Well I can't get that 5mm allen bolt out that holds it in. I can see it from above and it doesn't appear stripped, but the bugger won't come out. Seems like they designed that bolt so the allen key only goes in a couple mm because I have cleaned it very thoroughly with a dentist's pick and brake cleaner, so I know it is squeaky clean. I tried coming at it from the top with 4' worth of extensions but same issue. Any tricks or tips on how to get 'er out? Thanks!

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84 300D
84 300SD

I could look at one of the transmissions I have on my shop floor and see what it looks like...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Best picture I have is this one



from this thread 722.303 in bits photo shoot

It is "just" a simple Allen head screw - sorry - I know these little things can be frustrating; give me an automatic gearbox instead of a bicycle any day of the week!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I tried searching for this process but came up empty handed so I thought I'd show how I did it.

It's behind the Oil Cooler Line, so I removed/moved that to get a bit easier access... then I disconnected the center bearing, took out the trans mount, and dropped the transmission down about three inches. I also removed the muffler out of the way.
After a bit of tapping with a hammer, some pb blaster, and enough room for a ridiculously big pair of Vice Grips, I was able to get the bugger out. Here is a view from above (thanks to a very tiny cellphone I managed to wiggle in there:

Now I just have to wait a week for the o-ring to come in from California and I'll be back on the road. (I covered the open ports with tape)

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84 300D
84 300SD

Did you try your local auto parts store?

I have bought those o-ring assortment kits from Harbor Freight, but the one in there seems a little thicker, and considering the hell I went through taking it out I didn't want to chance it. Actually, could I just use some RTV gasket sealant on that so I don't have to think/work about it? I don't like the idea of it, but if I have to drop the transmission again because of it leaking there, I will just scrap this car.... don't wanna do that though.
Any Idea what I could sell this for as a parts car? The engine runs fantastic, the interior is pretty good shape, but the body is crap.

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84 300D
84 300SD

Sometimes i wonder if I would have ever bothered building a garage and putting in a lift if I didn't buy a 1981 300D about 10 years ago ...

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

Well I tried using several o-rings, and about 4 quarts of oil later I'm still leaking.
I somehow completely forgot that I have a Mercedes dealer nearby and that they sell parts, so I just went on over and picked up the o-ring.

It seems that the o-ring on there shrunk quite a bit, as the o-ring I bought is significantly thicker than any normal/standard o-ring.

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84 300D
84 300SD